Catalyst composition for making ultra high molecular weight poly (alpha-olefin) drag reducing agents

ABSTRACT

A catalyst consisting essentially of at least one tertiary monophenyl amine having a formula R1R2N-aryl, where R1 and R2 are the same or different, and each is a hydrogen, an alkyl, or a cycloalkyl group, where at least one of R1 and R2 contain at least one carbon atom; at least one titanium halide having a formula TiXm, where m is from 2.5 to 4.0 and X is a halogen containing moiety; and at least one cocatalyst having a formula AlRn Y3-n where R is a hydrocarbon radical, Y is a halogen or hydrogen, and n is 1-3. Further, the catalyst is absent of a carrier or support.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.15/349,351 filed Nov. 11, 2016, now issued as U.S. Pat. No. 9,969,826which claims the benefit of U.S. Provisional Patent Application No.62/257,357 filed Nov. 19, 2015.

TECHNICAL FIELD

Embodiments of the present disclosure generally relate to the productionof drag reducing agents for use in hydrocarbon conduits, and morespecifically relate to a catalyst composition for making ultra highmolecular weight poly(α-olefin) drag reducing agents.

BACKGROUND

In the petroleum industry, hydrocarbon fluids are transported through aconduit at a very high flow rate. This creates a lot of turbulence andwall friction, which cause fluid flow pressure drops. To overcome thispressure drop, a lot of mechanical energy is required. Thus, thetransport of the hydrocarbon fluid is an economic challenge. Ultra highmolecular weight (UHMW, molecular weight (MW)≥10⁶) poly(α-olefin)homopolymers and copolymers, in the form of drag reducing agents (DRAs),have been used to combat this challenge. The DRAs reduce theturbulence-mediated friction and eddies, which, in turn, decrease thepressure drop. Specifically, when injected into a stream of hydrocarbonfluid flowing through a pipeline, DRAs enhance the flow of the stream byreducing the effect of drag on the liquid from the pipeline walls. This,in turn, creates better streamlining for the flow in the pipe, increasesthe conservation of energy, and reduces the costs of pipeline shipping.

DRAs are produced using transition metal catalytic polymerizationprocesses; however, the catalytic activity from conventional catalystsis substandard. Moreover, other DRA synthesis processes require that thepolymerization be performed at cryogenic temperatures, which is alsocostly and inefficient. Further, obtaining DRAs with the requisitedegree of drag reduction has also been challenging.

SUMMARY

Accordingly, ongoing needs exist for improved DRAs, as well as improvedprocesses and improved catalyst systems for synthesizing DRAs.

In one embodiment, a method of producing ultra high molecular weight(UHMW) C₄-C₃₀ α-olefin drag reducing agent (DRA) is provided. The methodincludes polymerizing in a reactor a first α-olefin monomer in thepresence of a catalyst and hydrocarbon solvent to produce the UHMWC_(4—)C₃₀ α-olefin polymer DRA. The catalyst consists essentially of atleast one tertiary monophenyl amine having a formula R¹R²N-aryl, whereR¹ and R² are the same or different, and each is a hydrogen, an alkyl,or a cycloalkyl group, where at least one of R¹ and R² contain at leastone carbon atom; at least one titanium halide having a formula TiX_(m),where m is from 2.5 to 4.0 and X is a halogen containing moiety; and atleast one cocatalyst having a formula AlR_(n) Y_(3-n) where R is ahydrocarbon radical, Y is a halogen or hydrogen, and n is 1-3. Further,the catalyst is absent of a carrier or support.

In another embodiment, a catalyst is provided. The catalyst consistsessentially of at least one tertiary monophenyl amine having a formulaR¹R²N-aryl, where R¹ and R² are same or different, and each is ahydrogen, an alkyl, or a cycloalkyl group, where at least one of R¹ andR² contain at least one carbon atom; at least one titanium halide havinga formula TiX_(m), where m is from 2.5 to 4.0 and X is a halogencontaining moiety; and at least one cocatalyst having a formula AlR_(n)Y_(3-n) where R is a hydrocarbon radical, Y is a halogen or hydrogen,and n is 1-3. Further, the catalyst is absent a carrier or support.

In yet another embodiment, a method of reducing drag in a conduit isprovided. The method includes producing a UHMW C₄-C₃₀ α-olefin copolymerDRA by polymerizing in a reactor a first α-olefin monomer in thepresence of a catalyst and a hydrocarbon solvent. The catalyst consistsessentially of at least one tertiary monophenyl amine having a formulaR¹R²N-aryl, where R¹ and R² are same or different, and each is ahydrogen, an alkyl, or a cycloalkyl group, where at least one of R¹ andR² contain at least one carbon atom; at least one titanium halide havinga formula TiX_(m), where m is from 2.5 to 4.0 and X is a halogencontaining moiety; and at least one cocatalyst having a formula AlR_(n)Y_(3-n) where R is a hydrocarbon radical, Y is a halogen or hydrogen,and n is 1-3. The method further includes introducing the UHMW C₄-C₃₀α-olefin polymer DRA into the conduit to reduce drag in the conduit.

Additional features and advantages of the described embodiments will beset forth in the detailed description which follows, and in part will bereadily apparent to those skilled in the art from that description orrecognized by practicing the described embodiments, including thedetailed description which follows, the claims, as well as the appendeddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart depicting a process for making a DRA inaccordance with one or more embodiments of the present disclosure; and

FIG. 2 is a schematic depiction of the experimental equipment set-upused to evaluate the drag reduction achieved by DRA embodiments of thepresent disclosure.

DETAILED DESCRIPTION

Embodiments of the present disclosure are directed to improved catalystsystems and a polymerization process that synthesize (UHMW) C₄-C₃₀α-olefin polymer drag reducing agents (DRAs) with improved percentagedrag reduction for a flowing hydrocarbon fluid.

Method embodiments for producing UHMW C₄-C₃₀ α-olefin polymer DRA maycomprise polymerizing in a reactor a first α-olefin monomer in thepresence of catalyst and hydrocarbon solvent. The UHMW C₄-C₃₀ α-olefinpolymer DRA may comprise a homopolymer, copolymer, or a terpolymer. In aspecific embodiment, the UHMW C₄-C₃₀ α-olefin polymer DRA is a copolymerproduced by copolymerizing the first α-olefin monomer with a secondα-olefin comonomer.

The first α-olefin and second α-olefin comonomers may include C₄-C₃₀α-olefins, or C₄-C₂₀ α-olefins, or C₆-C₁₂ olefins. In one embodiment,the first α-olefin and second α-olefin comonomers are differentα-olefins selected from ethylene, propylene, 1-butene,4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene,1-tetradecene, and combinations thereof.

The solubility of DRAs in hydrocarbons is an important factor whichaffects the efficiency of the DRA. Without being bound by theory, DRAsproduced from the combination of a short chain α-olefin (for example, aC₂-C₆ α-olefin) and a long chain α-olefin (for example, a C₈—C₁₂α-olefin) has demonstrated improved solubility in hydrocarbons andthereby improved drag reduction efficiency. In one embodiment, the firstα-olefin comonomer is 1-hexene and the second α-olefin comonomer is1-dodecene. Various molar ratios are contemplated for the first α-olefinand second α-olefin comonomers. In one embodiment, the α-olefin monomersare 1-hexene and 1-dodecene present in a 1:4 to 4:1 molar ratio, or a1:2 to 2:1 molar ratio, or a 1:1 mole ratio.

Embodiments of the present catalyst used in the polymerization mayinclude a tertiary monophenyl amine, a titanium halide, and acocatalyst. In specific embodiments, present catalyst consists of orconsists essentially of the tertiary monophenyl amine, a titaniumhalide, and a cocatalyst. In additional embodiments, the catalyst isabsent of a carrier or support.

The tertiary monophenyl amine may have the formula R¹R²N-aryl, where R¹and R² are the same or different, and R¹ and R² may each be a hydrogen,an alkyl, or a cycloalkyl group with the proviso that at least one of R¹and R² contains at least one carbon atom. The aryl group may besubstituted or unsubstituted. Examples of the tertiary monophenyl aminemay include but are not limited to N,N-diethylaniline,N-ethyl-N-methylparatolylamine, N,N-dipropylaniline,N,N-diethylmesitylamine, and combinations thereof. In one embodiment,the tertiary monophenyl amine is N,N-diethylaniline.

The titanium halide has the formula TiX_(m), where m is from 2.5 to 4.0and X is a halogen containing moiety. In one embodiment, the titaniumhalide catalyst is crystalline titanium trichloride, for example, in thefollowing complex TiCl₃.1/3AlCl₃, which is prepared by reducing titaniumtetrachloride (TiCl₄) with metallic aluminum (Al).

The cocatalyst may be an organoaluminum compound having the formulaAlR_(n) Y_(3-n) where R is a hydrocarbon radical, Y is a halogen orhydrogen, and n is 1-3. Representative examples of such organoaluminumcompounds which can be used alone or in combination are trimethylaluminum, triethyl aluminum, tri-n-propyl aluminum, tri-n-butylaluminum, tri-isobutyl aluminum, tri-n-hexyl aluminum,tri(2-methylpentyl) aluminum, tri-n-octyl aluminum, diethyl aluminumhydride, diisobutyl aluminum hydride, diisoproyl aluminum chloride,dimethyl aluminum chloride, diethyl aluminum chloride, diethyl aluminumbromide, diethyl aluminum iodide, di-n-propyl aluminum chloride,di-n-butyl aluminum chloride, and diisobutyl aluminum chloride. In oneembodiment, the cocatalyst is diethyl aluminum chloride.

Various amounts are contemplated for the catalyst components. Forexample, the tertiary monophenyl amine may be present in an amount offrom 0.1 millimole (mmol) to 2 mmol, or from 0.25 mmol to 1 mmol, orfrom 0.4 mmol to 0.8 mmol, or 0.5 mmol. Moreover, the titanium halidemay be present in an amount of from 0.1 millimole (mmol) to 1 mmol, orfrom 0.2 mmol to 0.8 mmol, or from 0.2 mmol to 0.5 mmol, or 0.25 mmol.Further, the cocatalyst may be present in an amount of from 0.2millimole (mmol) to 5 mmol, or from 0.5 mmol to 2.5 mmol, or from 0.8mmol to 1.5 mmol, or 1.0 mmol. The molar ratio of the cocatalyst totitanium halide may be from 1:1 to 10:1, or 2:1 to 8:1, or 3:1 to 5:1,or 4:1. Alternatively, the molar ratio of the cocatalyst to tertiarymonophenyl amine may be from 1:1 to 5:1, or 2:1 to 4:1, or 2:1.

The hydrocarbon solvent may include various solvent compositions. Forexample, a halogenated hydrocarbon solvent such as ethylene dichlorideis contemplated for the hydrocarbon solvent. Moreover, the hydrocarbonsolvent may include aromatic solvents, such as toluene, or cumene.Commercial examples of suitable aromatic solvents include Koch Sure Sol®100 and KOCH Sure Sol® 150. Other solvents may include straight chainaliphatic compounds (for example, hexane and heptane), branchedhydrocarbons, cyclic hydrocarbons, and combinations thereof. As will bedescribed in the paragraphs to follow, the addition of solvent and thetiming of solvent addition may impact the final properties of the DRA.

Referring to the embodiment depicted in FIG. 1, the method 100 ofproducing the DRA includes the step 110 of delivering the first driedα-olefin monomer and optionally the second α-olefin monomer to a reactoror series of reactors. In specific embodiments, the reactor may includea stirring rod or a similar agitation device. In multiple embodiments,the reactor is a continuous, batch, or semi-batch stirred tank reactor.These olefin monomers may be included in the presence of solvent andoptionally in the presence of a scavenger, such as triisobutylaluminum(TIBA). In specific embodiments, the reactor may be subjected to aninert gas. For example, the first α-olefin monomer and the secondα-olefin may be delivered to the reactor under argon flow.

Referring again to FIG. 1, the catalyst may be activated prior todelivery to the reactor. In one embodiment, the activation step 120 mayinvolve activating the titanium halide and cocatalyst by heating priorto delivery to the reactor. Various temperatures are contemplated, forexample 30 to 60° C., or 40° C. In another embodiment, the tertiarymonophenyl amine is mixed with the titanium halide and the cocatalystduring the activation step. Alternatively, the tertiary monophenyl aminemay be added to the reactor separate from the titanium halide andcocatalyst either before or after the addition of activated titaniumhalide and cocatalyst to the reactor.

Next, the activated catalyst may be added to the reactor 130 whichinitiates the polymerization 150. The polymerization may occur at orless than ambient temperature. In a specific embodiment, thepolymerization may occur at ambient temperature. Without being limitedto specific advantages, performing the polymerization at ambienttemperature reduces process costs in comparison to other conventionalprocesses which operate under cryogenic conditions.

In yet another embodiment, the polymerization may occur in an argonatmosphere for a duration of 4 to 6 hours with a reaction temperature of15 to 25° C. In at least one embodiment, the polymerization in argon mayoccur with a reaction temperature of −20 to 30° C. Further, in at leastone embodiment, the polymerization time in argon may extend for aduration of 30 minutes to 12 hours. As stated previously, the reactormay be agitated by a mechanical stirring device. For example, thestirring speed may be between 400 to 900 revolutions per minute (rpm),600 to 800 rpm, or 700 rpm.

Referring to FIG. 1, the hydrocarbon solvent 140 may be added at once,gradually, or at multiple times during the process. For example,hydrocarbon solvent may be added in bulk 142 prior to the polymerizingstep 150. Alternatively, the hydrocarbon solvent may be added graduallythroughout the polymerization process, or after the start of the “rodclimbing effect” 160. The rod-climbing effect refers to a phenomenonresulting from mechanical stirring in the reactor when (i) the viscosityof the reaction mixture exceeds a certain critical value, and (ii) thenormal forces with respect to the surface of the reaction mixture exceedthe corresponding tangential forces, thereby causing the mixture toascend or climb the stirring rod.

Referring again to FIG. 1, the reactor may be quenched with methanol 170thereby at least partially terminating the polymerization process. Atwhich point, the UHMW C₄-C₃₀ α-olefin DRA is produced 180. In specificembodiments, the DRA may have a non-crystalline or amorphous structure.Alternative quenching procedures are contemplated as are alternativeprocedures to terminate the polymerization process.

Without being bound by theory, further branching, for example, longchain branching, may enhance the solubility of the DRA. This increasedbranching may be quantified in part by the molecular weight distribution(MWD) metric. In one or more embodiments, the UHMW C₄—C₃₀ α-olefincopolymer drag reducing agent may have an MWD of at least 2.0, where MWDis defined as M_(w)/M_(n) with M_(w) being a weight average molecularweight and M_(n) being a number average molecular weight. In anotherembodiment, the MWD may be at least 3.25. Moreover, the UHMW C₄—C₃₀α-olefin polymer drag reducing agent has a weight average molecularweight (M_(w)) of at least 1.5×10⁶ g/mol, or at least 2.0×10⁶ g/mol, orat least 2.5×10⁶ g/mol. The polydispersity index (PDI) may be at least2.0.

For additional details regarding the embodiments of the presentdisclosure, the following examples are provided.

EXAMPLES

All the synthesis procedures and manipulations were done under inertenvironment using argon, standard Schlenk technique, and a glove box.Toluene, 1-hexene (C₆), and 1-dodecene (C₁₂) were dried by contactingwith an activated 4A molecular sieve at room temperature overnight. Themolecular sieve was activated at 230° C.

Reference Example

1-hexene (C₆) and 1-dodecene (C₁₂) were copolymerized using acomputer-interfaced, AP-Miniplant GmbH laboratory-scale reactor set-up.The reactor consists of a fixed top head and a one-liter jacketed Büchiglass autoclave. The glass reactor was baked for 2 hours (h) at 120° C.Then, it was purged with nitrogen four times at the same temperature.The reactor was cooled from 120° C. to room temperature.

Specifically, the desired volume of 1-hexene (C₆), dodecene (C₁₂), anddried toluene dissolved in 200 milliLiters (mL) of dried n-hexane and1.0 mL of 1.0 M triisobutylaluminum (TIBA) were transferred to thereactor under mild argon flow.

The required amount of solid TiCl₃.1/3AlCl₃ dissolved in dried toluenewas pre-activated with a calculated amount of diethyl aluminum chloride(DEALC) in a Schlenk flask by heating them at 40° C. for 30 minutes(min).

The whole volume of the pre-activated catalyst solution was siphonedinto the reactor under mild argon flow to start polymerization for 5hours with reaction temperature and stirrer speed set at 20° C. and 700rpm, respectively. Additionally, 200 mL of dried toluene was added whenthe rod-climbing effect started. The reaction mixture was quenched byadding methanol with vigorous agitation.

Upon completion of the polymerization trial as described previously, thereactor was opened, the resulting honey-like reaction mixture was storedin a bottle, and its weight was determined. The glass reactor vessel wascleaned using technical grade toluene for the next trial.

The synthesized C₆-C₁₂ reference copolymer was characterized in terms ofweight average molecular weight M_(w) using high temperature gelpermeation chromatography (GPC) (Polymer Lab GPC 220, UK).

The following table lists properties of the DRAs produced by the priorReference Example as well as additional examples. In transitionmetal-catalyzed olefin polymerization, M_(w) and catalyst productivityare approximately inversely related. However, catalyst productivity is acomplex function of monomer and co-monomer concentration, macro-mixingand micro-mixing, and temperature in combination with thermodynamic,kinetic, and mass transfer limitations. Preferably, the catalystproductivity is maximized while maintaining the M_(w) above 1×10⁶ g/mol.

TABLE 1 Summary of DRA synthesis (polymerization) trials Total Catalystmonomer productivity Synthesis Polymerization conversion g DRA/(g M_(w)× 10⁶ of Examples Conditions (%) cat h) DRA (g/mol) MWD ReferenceTiCl₃•⅓AlCl₃ (pre-catalyst) was 38.46 56 2.37 3.81 example activatedwith DEALC cocatalyst by heating for 30 min to achieveDEALC:TiCl₃•⅓AlCl₃ having a molar ratio >1. Total reaction volume beforedilution = 200 mL. Also, 200 mL of dried toluene was added after 30 minof reaction when the rod-climbing effect was observed to just develop.1-hexene (C₆) was copolymerized with dodecene (C₁₂) at 20° C. at a givenmolar ratio of C₆:C₁₂. 1 mL TIBA used as scavenger. Reactor stirrerspeed = 700 rpm. Polymerization trial duration = 5 h. Example 1 Thisexample was conducted the same 53.15 77 1.70 3.39 as the ReferenceExample, with the exception that 0.5 mmol of N,N- diethylaniline wasused during the activation of the pre-catalyst. Example 2 This examplewas conducted the same 35.93 52 3.42 3.48 as Example 1; however, 200 mLof dried toluene was added dropwise throughout the polymerization trialwhen the rod-climbing effect was observed to just develop. Example 3This example was conducted the same 54.38 79 2.43 3.82 as Example 1 withthe following difference; 30 mL of cumene (a viscosity reducing agent)and 170 mL of toluene were added after 30 min of reaction when therod-climbing effect was observed to just develop. Example 4 TiCl₃•⅓AlCl₃and 0.5 mmol of 45.83 67 2.23 2.63 N,N-diethylaniline were firstactivated for 30 min. Then, DEALC was added and activated for 30 minbefore feeding into the polymerization reactor. The polymerization wasconducted as illustrated in the Reference Example. Example 5TiCl₃•⅓AlCl₃, 0.5 mmol of 33.90 49 2.50 2.08 N,N-diethylaniline, andDEALC were activated for 30 min before feeding into the polymerizationreactor. The polymerization was conducted as illustrated in theReference Example. Example 6 This example was conducted the 21.48 392.63 3.02 same as Example 1; however, after 30 min (when the rod-climbing effect was observed to just develop), 0.5 mmol of benzophenone(a Lewis base) was added to the reactor. Finally, after another 5 min,190 mL of dried toluene fed the reactor. Example 7 Step 1: 0.5 mmol of21.59 16 3.85 2.18 benzophenone reacted with DEALC for 30 min. Step 2:0.5 mmol of N,N- diethylaniline is reacted with the benzophenone/DEALCreaction mixture for 30 min. Step 3: the final catalyst was formulatedby reacting the Step 2 reaction mixture with TiCl₃•⅓AlCl₃ for 30 min.The polymerization was conducted as illustrated in the ReferenceExample. Example 8 Step 1: 0.5 mmol of N,N- 11.53 17 1.85 2.36diethylaniline reacted with DEALC for 30 min Step 2: 0.5 mmol ofbenzophenone reacted with the Step 1 reaction mixture for 30 min. Step3: the final catalyst was formulated by reacting the Step 2 reactionmixture with TiCl₃•⅓AlCl₃ for 30 min. Step 4: The polymerization wasconducted as illustrated in the Reference Example. Example 9 Step 1: 0.5mmol of 11.18 16 2.60 2.58 benzophenone and 0.5 mmol ofN,N-diethylaniline were reacted with DEALC for 30 min. Step 2: the finalcatalyst was formulated by reacting the Step 1 reaction mixture withTiCl₄•⅓AlCl₃ for 30 min. Step 3: The polymerization was conducted asillustrated in the Reference Example. DRA1 Commercial as-synthesized2.8  3.02 polyisobutylene (PIB) available from (viscosity ScientificProducts Inc., catalog average) number: 040D. DRA2 ConocoPhillips LP100: 2.20 2.33 poly(1-decene) UHMW polymer

When comparing Example 1 to the Reference Example, it is clear that theaddition of tertiary monophenyl amine (N,N-diethylaniline) in Example 1improves the monomer conversion and catalyst productivity. Moreover,when comparing Example 2 to Example 3, it is clear that the addition ofhydrocarbon solvent such as cumene and toluene at the beginning of therod climbing effect as in Example 3 is better at monomer conversion andcatalyst productivity than Example 2 where hydrocarbon solvent isincluded dropwise throughout the process. Additionally, when comparingExamples 1, 3, and 4 to the Reference Example, an increase in catalystproductivity is observed. Without wishing to be bound by theory, thehigher catalyst productivity in Examples 1, 3, and 4 over the ReferenceExample is believed to be the result of the interaction and complexationof the precatalyst TiCl₃.1/3AlCl₃ with N,N-diethylaniline.N-N-diethylaniline is sterically and electronically hindered. The sterichindrance originates from the ethyl substituents on the N heteroatom.Similarly, the phenyl group, which is an electron-withdrawingsubstituent, reduced the electron density on the basic N heteroatom andintroduces electronic effect. This coherent and combined steric andelectronic effect increases the catalyst productivity compared to theReference Example by playing the role of a catalyst promoter. Increasedcatalyst productivity results in a greater production volume and allowsfor a commensurate reduction in production cost.

Adjustments to the process parameters may also adversely affect thecatalyst productivity. Specifically, in Example 5 the precatalystTiCl₃.1/3AlCl₃, N,N-diethylaniline, and DEALC were all contactedtogether. This results in the Lewis base (N,N-diethylaniline) beingavailable to coordinate simultaneously with both TiCl₃.1/3AlCl₃ andDEALC. This adversely affects the alkylation of TiCl₃.1/3AlCl₃ by DEALCand the subsequent creation of open coordination sites at the titaniumto form active sites which results in a catalyst productivity drop.Further, in Example 2 the 200 mL of toluene was added dropwisethroughout the polymerization trial unlike in the Reference Example andExamples 1, 3, and 4 where the toluene was added as a single bolus assoon as the rod-climbing effect was noted. The drop-wise addition allowsthe polymerization to turn highly viscous which restricts the desiredmacromixing and micromixing of the growing polymer chains which containthe active center with the unreacted monomer. This results in acomparative decrease in catalyst productivity. Finally, in Examples 6-9benzophenone was added. The benzophenone decreased both the rates ofpropagation and termination, albeit the termination rate decreased morethan the propagation resulting in a net decrease in catalystproductivity. However, reduction in catalyst productivity may result ina commensurate improvement in drag reduction performance. As such,through process adjustments, a process of forming a DRA with desirabledrag reduction performance and acceptable catalyst productivity may beachieved.

Drag Reduction Tests

The drag reducing performance of the C₆-C₁₂ reference UHMW copolymer wasevaluated using the experimental set-up shown in FIG. 2. This consistsof a horizontal stainless steel pipeline of 0.5 inch outer diameter(OD=0.01270 m) and 0.4 inch inner diameter (ID=0.01016 m). The firstpressure sensor 220 was located around 4 meters (m) from the kerosenehydrocarbon fluid inlet 216. The second pressure sensor 222 was located1.5 m from the first pressure sensor 220. The DRA injection point 218 islocated 20 cm from the kerosene fluid inlet 216. The pressure gradientwas measured using a high accuracy differential pressure transducer 224(Siemens) with a manufacturer states error of less than 0.065%. The flowof the kerosene fluid, which was stored initially in a tank 200, wasdelivered and controlled by ball valves 202, 209, pump 204, and flowcontrol valve 206. The flow rate of kerosene was measured using a highaccuracy vortex flow meter 208 with a manufacturer states error of lessthan 2%. The temperature of the liquid was measured using a resistancetemperature detector (RTD) temperature sensor 226 located at the end ofthe test section. Downstream of the temperature sensor 226, a portion ofthe DRA infused kerosene fluid was separated at splitter 230 with aportion being discarded in waste tank 234 and another portion recycledto the kerosene tank 200.

Referring again to FIG. 2, the DRA polymer solution with liquid keroseneas a solvent, which were the DRAs produced in the Examples listed inTable 1, were injected into the test pipe using a diaphragm dosing pump212. The DRA polymer solution concentration was determined using thepolymer content in the reaction mixture and configured to be 120 partsper million (ppm) of DRA in the test pipe after mixing. The flow rate ofthe DRA polymer solution was controlled with a variable speed drive 214,lined-up with the pump 212. The pump 212 was calibrated before eachexperiment using different speeds. The pump speed was varied from 0 to1, 400 rpm. The pump flow rate was changed between 0.01 and 2 L/min withan accuracy of 2-4%. The DRA polymer solution was introduced into thekerosene feed at DRA injection point 218, which is a single hole at thetop of the pipe having a diameter of 2 mm, located 20 cm upstream of thekerosene inlet 216.

The drag reducing performance tests of the C₆-C₁₂ reference UHMWcopolymer were conducted using a kerosene flow rate of 10 L/min. Thismakes the average velocity of kerosene in the pipe about 2.1 m/s (6.8ft/s) with a Reynolds number about 18,850, which indicates highturbulent flow.

The effectiveness of drag reduction is expressed by percentdrag-reduction (% DR) defined as follows:

$\begin{matrix}{{\%\mspace{14mu}{DR}} = {\frac{{\Delta\; P_{withoutDRA}} - {\Delta\; P_{withDRA}}}{\Delta\; P_{withoutDRA}} \times 100}} & (1)\end{matrix}$

-   -   where ΔP_(withDRA) and ΔP_(withoutDRA) are pressure drops with        and without the drag-reducing agent, respectively.

Table 2 as follows summarizes drag reduction for the Examples of Table1.

TABLE 2 Summary of DRA performance trials DRA concentration in thepipeline Level of drag reduction* DRA trials (ppm) (% DR) Reference 12056.5 example Example 1 120 44.0 Example 2 120 58.5 Example 3 120 36.0Example 4 120 34.0 Example 5 120 39.0 Example 6 120 43.0 Example 7 12054.5 Example 8 120 51.0 Example 9 120 49.5 DRA1 120 28.0 DRA2 120 47.8

When comparing Examples 1 through 9 and the Reference Example to thecommercially available DRA1, a clear improvement in the percentdrag-reduction is evident. Similarly, Examples 2 and 7 through 9 whencompared to the commercially available DRA2 exhibit a clear improvementin the percent drag-reduction as well. Improvement in the level of dragreduction results in a reduction in required pumping energy and acommensurate savings in electricity and associated costs.

It should be apparent to those skilled in the art that variousmodifications and variations can be made to the described embodimentswithout departing from the spirit and scope of the claimed subjectmatter. Thus it is intended that the specification covers themodifications and variations of the various described embodimentsprovided such modification and variations come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A catalyst consisting essentially of: at leastone tertiary monophenyl amine having the formula R¹R²N-aryl, where R¹and R² may each be a hydrogen, an alkyl, or a cycloalkyl group with theproviso that at least one of R¹ and R² contains at least one carbonatom; at least one titanium halide having a formula in accordance withTiCl₃.1/3AlCl₃; and at least one cocatalyst having a formulaAlR_(n)Y_(3-n) where R is a hydrocarbon radical, Y is a halogen orhydrogen, and n is 1-3, where the catalyst is absent a carrier orsupport.
 2. The catalyst of claim 1 where at least one tertiarymonophenyl amine is selected from the group consisting ofN,N-diethylaniline, N-ethyl-N-methylparatolylamine, N,N-dipropylaniline,N,N-diethylmesitylamine, and combinations thereof.
 3. The catalyst ofclaim 1 where the cocatalyst is Al(CH₂CH₃)₂Cl.
 4. The catalyst of claim1 where the cocatalyst comprises one or more organoaluminum compoundsselected from the group consisting of trimethyl aluminum, triethylaluminum, tri-n-proyl aluminum, tri-n-butyl aluminum, tri-isobutylaluminum, tri-n-hexyl aluminum, tri(2-methylpentyl) aluminum,tri-n-octyl aluminum, diethyl aluminum hydride, diisobutyl aluminumhydride, diisoproyl aluminum chloride, dimethyl aluminum chloride,diethyl aluminum chloride, diethyl aluminum bromide, diethyl aluminumiodide, di-n-propyl aluminum chloride, di-n-butyl aluminum chloride, anddiisobutyl aluminum chloride.
 5. The catalyst of claim 1 where thetertiary monophenyl amine comprises N, N-diethylaniline.
 6. The catalystof claim 1 where the aryl group is substituted.
 7. The catalyst of claim1 where the aryl group is unsubstituted.
 8. The catalyst of claim 1where the molar ratio of the cocatalyst to titanium halide is from 1:1to 10:1.
 9. The catalyst of claim 1 where the molar ratio of thecocatalyst to tertiary monophenyl amine is from 1:1 to 5:1.